1. Field of the Invention
The present invention generally relates to a method of making halogen lamps and halogen lamp bulbs, as well as other analogous lamps and objects. The present invention also relates to apparatus used in a method of making halogen lamps and halogen lamp bulbs, as well as other analogous lamps and objects.
2. Background Information
During the operation of a halogen lamp, an equilibrium is established between the formation and decay of tungsten halides from the tungsten vapor from the filament and the mixture of halogen and inert glass. The decay reaction thereby takes place at higher temperatures than the formation reaction, so that the tungsten is re-deposited on the filament. If this cycle is disrupted by contaminating components, the tungsten, instead of being deposited on the filament, is deposited on the inside of the glass bulb as a reflective black coating, and the lamp becomes unusable.
Darkening or blackening in tungsten-halogen lamps occurs because as a result of reactions of the halogen gas with the glass, the amount of halogen gas that must be present to maintain the halogen cycle is reduced to the extent that the halogen cycle collapses and tungsten is deposited as a black coating on the inside of the glass instead of on the filament.
For numerous uses of glass objects, in particular glass tubes or flat glass plates as well as of the shaped bodies formed from the (semi-finished) glass objects, the glass is required to have certain characteristics, in particular of certain surface characteristics, such as for example a high chemical resistance, for example.
Some glass objects that require the specified surface characteristics are listed by way of example in the following list:                for lighting purposes, e.g. halogen lamps,        for discharge lamps,        for the construction of chemical plants,        in flow meters for chemically aggressive media,        for analytical purposes (e.g. test tubes, titration cylinders etc.)        for reagent bottles for special purposes,        for coating measuring electrodes in aggressive media,        for use as components for biotech reactors        containers for medical purposes (e.g. ampoules, bottles, injection bottles, cylinder ampoules etc.),        as primary packaging for pharmaceutical products,        as components for display applications.        
Of course the prior art describes glass objects, in particular glass objects made of silica glass (quartz glass, SiO2 glass), as semi-finished products for the forming of hollow molded articles which have, among other things, high chemical resistance. However, such glass objects, are very complex and expensive to produce on account of the high melting point of the SiO2 glass. They can also be produced only with limited optical qualities and are less suited for use as mass produced items. Such glass objects can also be transformed only with very special equipment, because on one hand the transformation temperatures are very high, and on the other hand the temperature range in which transformations are possible is very narrow.
Therefore semi-finished glass objects made of silica glass cannot be produced with sufficient quality and economy for mass-production applications.
Therefore glass with a lower melting point is generally used for products manufactured on an industrial scale, such as borosilicate glass or soda-lime glass. These types of glass can be manufactured and transformed easily.
The prior art also discloses methods that modify in particular the surfaces of glass objects made of glass that has a low melting point.
For example, the prior art described hot forming methods for the production of glass objects from glass melts in which the surfaces of the glass objects are exposed at least partly during the hot forming to a specified gas atmosphere, and the surface characteristics of the glass can thereby be modified in a controlled manner.
U.S. Pat. No. 4,717,607 describes a method for the manufacture of glass tubes in which the glass surface is chemically leached and thereby modified. During the drawing of the glass tube, the inner surface of the glass tube is thereby exposed to a gas mixture of a organo-fluoride gas, e.g. 1,1-difluoroethane, and an oxidizing gas, e.g. air. The fluorine released by combustion of the gas mixture reacts with the alkali and alkaline earth metal ions in the glass surface, forming alkali and alkaline earth compounds that are then exhausted out through the gas tube.
The prior art also describes methods in which the surface of the glass is chemically leached by introducing into the still hot glass tube an appropriately aggressive gas, typically SO2 or HCl gas, which leads to surface reactions and a reduction of the alkali content in the surface.
Such dealkalization methods are described, for example, in H. A. Schaeffer et al., Glastech.Ber. 54 (1981), No. 8, pp. 247-256. The disadvantage of all these methods is that most of the gases used are toxic, whereby the glass surface can still contain traces of these aggressive reagent gases after the chemical treatment, and the surface structure of the glass can be damaged, which results in a rough surface and the presence of active centers on the surface. The use of such aggressive gases is also undesirable from the point of view of compliance with environmental and occupational health and safety requirements. During the transformation of such leached glass tubes, particles can come detached from the porous, damaged surfaces. Moreover, prior to the use of the leached glass tubes, a washing process is necessary to remove the reaction products. This washing process requires a subsequent drying and disposal of the reaction products, i.e. it increases the costs for the production of the semi-finished glass tubes.
U.S. Pat. No. 3,314,772 discloses another method for the removal of alkaline elements from glass with a low melting point by fluoridation using compounds that contain fluorine, e.g. aqueous HF solutions, which has the same typical disadvantages as the other dealkalization methods described above.
To eliminate the disadvantages of the dealkalization methods, the prior art also describes the manufacture of tubular glass containers from glass with a low melting point that are used in particular as packaging for pharmaceutical materials, and are provided on their inner surface with a silicon dioxide (SiO2) coating that makes it as inert as a quartz glass surface (M. Walther, “Packaging of sensitive parenteral drugs in glass containers with a quartz-like surface” in Pharmaceutical Technology Europe, May 1996, Vol. 8, No. 5, pp. 22-27.
The coating of the internal surface of the molded glass objects is thereby done by chemical precipitation of the oxide coating material from its gas phase, in particular by means of a vacuum-assisted plasma CVD method (PECVD=Plasma Enhanced Chemical Vapor Deposition), in particular (DE 296 09 958 U1) and a pulsed plasma (PICVD=Plasma Impulse Chemical Vapor Deposition).
For this purpose, the finish-molded containers, i.e. the formed glass objects themselves, are coated internally. To do that, each formed glass container must be individually subjected to a complex, time-consuming and expensive coating process appropriate to its shape.